This inention relates generally to medical devices for insertion and extended stay within an anatomical pathway, and more particularly to endotracheal tubes wherein the depth of placement within the intubated pathway is of particular concern, necessitating prevention and detection of malposition during use.
Endotracheal tubes are widely known and extensively used in surgical and intensive care settings. Their typical use is to provide respiratory support of patients in physically comprised conditions such as during and following anesthesia or during the course of a serious injury or disease process.
Conventionally, the endotracheal tube comprises an elongated tubular apparatus having a centrally located primary passage and, when placed, has a forward portion and end residing within the trachea and a rearward portion and end residing outside the breathing passage, extending through the mouth or nose. A circumferentially expansible cuff is used in most varieties of endotracheal tubes, residing near its forward end, and is inflated by means of an associating inflation circuit. Beginning with a check valve and test balloon at one end, a fluid conducting element joins a secondary passage provided within the tube wall which in turn is forwardly in fluid communication with the cuff. During intubation the cuff is inflated to provide a seal between the endotracheal tube and the wall of the trachea, thereby allowing oxygen and other gases to pass from the endotracheal tube and into the lungs without escape through the mouth or nose of the patient. Additionally, a radiopaque filament is incorporated within the tube wall, usually the entire length of the tube, and provides for radiographic visualization of the endotracheal tube in reference to associating anatomical landmarks.
Of critical importance to patient welfare is a correct placement of the endotracheal tube forward end and the expansible cuff within the trachea. A particular problem, especially apparent during prolonged tube placement, is the risk of unintentional displacement and malposition of the endotracheal tube. It is the common practice to tape the tube in place immediately upon intubation and to retape the tube as indicated following radiographic determination of its forward portion within the trachea. (A position of 3 to 4 centimeters above the trachea bifurcation is regarded as safe in preventing unwanted contact of the forward end or cuff with the tracheal carina or vocal cords, respectively.) It is an equally common practice to frequently retape the tube as needed to replaced soiled and worn tape, when moving the tube from one side of the mouth to the other side, or when skin integrity is adversely affected by the tape's adhesive surface. Adding to the displacement and malposition risk is the potential that secretions will adversely act on the adhesive surface of the tape as to allow undetected slippage of the endotracheal tube to occur.
A particular problem encountered in the event of endotracheal tube malposition is the problem of disproportionate ventilation of one lung as opposed to the other lung by advancement of the forward end of the endotracheal tube within a mainstem bronchus. Serious sequelae and prolonged and complicated hospitalization may result. An additional radiograph is often taken to verify correct tube readjustment when the position of the endotracheal tube is in question, adding both expense and additional radiation exposure to the list of accompanying problems.
Preceding the present invention, methods used to establish, and identify on an ongoing basis, correct tube placement have proven unsatisfactory. Ink markings manually placed on the endotracheal tube wall adjacent to its point of entrance within the intubated pathway are either hard to place because of interfering tape, or can be rubbed off, covered, or lifted off when retaping. Wall markings printed on the endotracheal tube designating increments of length from a given wall location to the forward end of the tube are also subject to loss and obscurity, and are additionally unsatisfactory in that the correct length is either forgotten or otherwise lost to use by other clinicians. A novel, but equally unsatisfactory method has been employed to mark the entrance point of the tube and consists of placing a suture through the wall of the tube adjacent to its point of entry within the intubated pathway and then circumferentially wrap and tie the suture in place about the tube body. This procedure is costly, time consuming, and often interferes with tape replacement. If not carefully placed, the suture acts to block a suction catheter, endoscope, or the like from passing through the primary passage of the endotracheal tube. All too often the inconvenience and inadequacies of these methods discourage the use of any marking system, underscoring the need for the invention herein described.